Use of osm4wiki links with any non-Wikipedia site as the referrer fail and return an error page rather than the map. This means that users who use osm4wiki links on a non-Wikipedia project (such as Commons), from a browser bookmark, or received by email or IM, will receive the error page.
Steps to reproduce:
1: Copy the link to an OSM entry on osm4wiki such as https://tools.wmflabs.org/osm4wiki/cgi-bin/wiki/wiki-osm.pl?project=en&article=National_Register_of_Historic_Places_listings_in_Hampshire_County%2C_West_Virginia.
2: Paste the link into a new browser tab or window, bookmark the link and use the bookmark, or use it from any site except a Wikipedia.
Expected behavior: The desired OSM map with NRHP locations would be displayed.
Actual behavior: An error page saying "Don't disturb Wikipedia. Thanks." is displayed.
I have confirmed that this is referrer-based by using a referrer spoofer to always send a Wikipedia page as the referrer to osm4wiki. This will result in the map being displayed normally rather than receiving the error page. The content of this error message makes it especially an issue, as it appears to indicate that the user was trying to do something malicious when they are not.